In keeping with Nicholas Hytner's refusal to play safe with the musical genre, this collaboration between Tori Amos and the dramatist Samuel Adamson – brilliantly staged by Marianne Elliott – is a ravishing fusion of theatrical arts.

Giving a feminist twist to a Victorian fairy tale by George MacDonald, it's a darkly droll coming-of-age piece that focuses on the heirs to two kingdoms and their reactions to grief.